The present invention relates to a method of grading an article of a given type, in particular a garment, formed by assembling a plurality of pieces.
Garments are generally made by assembling a plurality of pieces which correspond to a base model or pattern and each of which is in the form of a plane developed area having a particular outline and optionally certain additional internal markers.
The size of a garment is determined mainly relative to particular measurements such as chest size, neck size, hip size, etc., and by the style that is to be given to the garment (tight-fitting or loose-fitting style, for example). The various measurements are organized into scales of sizes or tables of measurements which differ depending on the targeted population.
For each piece of a garment, grading is thus the operation that consists in obtaining, from a base model corresponding to a base size, additional patterns that are of different (larger or smaller) sizes as a function of a given scale of measurements, but that remain similar, as regards their shapes, to the base model.
Grading then makes it possible to obtain the geometrical layouts of the pieces in the various sizes, which is necessary for preparing to cut the pieces out from the material out of which the garment is to be made, which material can, for example, be a woven fabric, leather, or any other desired natural or synthetic material.
Grading also applies to all of the other fields in which articles of different sizes are made that must correspond to a base model, such as, for example, the field of shoemaking.
When grading is applied to a garment, it is already known that characteristic points or “outline points” can be marked on the pieces of the base model, knowledge of the outline points making it possible to reconstruct, in full, the images of the pieces, optionally also with markers internal to said pieces.
For each different size, grading thus consists in determining the characteristic points corresponding to the characteristic points of the base model, and in applying grading rules with reference to a given scale of measurements. On the basis of the characteristic points determined in this way, the image of the base model for the size in question can be plotted automatically, which enables automatic cutting-out to be performed subsequently.
Since numerous grading rules exist for each type of garment and for each scale of measurements, the main difficulty in applying such a method lies in choosing the proper grading rule for each characteristic point of each piece of the garment, on the basis of a given base size. Often, the knowledge and know-how of experienced staff is used.